Abstract
Cemented total hip arthroplasty (THA) has become an extremely successful operation with excellent long-term results. Although it always remained a popular choice for the elderly patients in many countries, recent trends show an increased use of non-cemented stems in all age populations in many national registries. So far, there has been no clear age associated recommendation, when a cemented stem should be used. Described major complications such as periprosthetic fractures are usually associated at age >75 years, in many registries. Uncemented stems perform better than cemented stems in recent registries; however, unrecognised intraoperative femoral fractures may be an important reason for early failure of uncemented stems. Experimental studies have indicated that intraoperative fractures do affect implant survival, in addition it has been shown that intraoperative and direct postoperative fractures increase the relative risk of revision during the first 6 postoperative months significantly. Furthermore it has been clearly shown, that uncemented stems were more frequently revised due to periprosthetic fracture during the first 2 postoperative years than cemented stems.
Although often associated reduction of femoral bone quality in especially female patients >60 years, uncemented fixation has become the standard in most scenarios worldwide. Based on the implant fixation type: metaphyseal vs. diaphyseal of various uncemented stems, major attention should be, however, drawn to the intraoperative bone quality during the broaching process, especially for metaphyseal fixation stem types. Although cementless distal fixation can be achieved in thick cortices still in many patients, the incidence of associated thigh pain needs to be considered for some implant types. Furthermore small femoral canals might generate certain implant-bone size mismatch in relation to the proximal femur, thus nonoptimal fixation could be achieved. Consequently proper implant planning is mandatory preoperatively.
In any cemented THA, a proper cementing technique is of major importance to assure longevity of implant fixation. This also includes proper implant sizing/ templating, ensuring an adequate cement mantle thickness, which might be restricted in a small diameter femur. The desired outcome is a cement interdigitation into cancellous bone for 2–3mm and an additional mantle of 2mm pure cement. Consequently proper planning in small diameter patients, prevents sizing problems, while in few cases special/individualised stem sizes might be considered.
In summary attention needs to be drawn on small diameter stems, to prevent fractures and achieve proper implant fixation, in both uncemented and cemented fixation types. Proper implant planning preoperatively might be more important than in usual cases, while sometimes individual /small implant types might become necessary.
